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Search for neutrinos from collapsing stars in Italy (a 30 years report) C. Castagnoli, K. Lande,

Search for neutrinos from collapsing stars in Italy (a 30 years report) C. Castagnoli, K. Lande, O. G. Ryazhskaya, O. Saavedra G. T. Zatsepin …..and many others. CNB. Supernova. Solar. Atmospheric. Sources.

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Search for neutrinos from collapsing stars in Italy (a 30 years report) C. Castagnoli, K. Lande,

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  1. Search for neutrinos from collapsing stars in Italy (a 30 years report) C. Castagnoli, K. Lande, O. G. Ryazhskaya, O. Saavedra G. T. Zatsepin …..and many others Vulcano 2008

  2. CNB Supernova Solar Atmospheric Sources Vulcano 2008

  3. During a stellar collapse, the neutrino luminosity (˜1053 erg/s) is comparable to the optical luminosity of the entire Universe Vulcano 2008

  4. Sun 1604 (Kepler) 1572 (Ticho) 1181 1054 (Crab) 1006 Vulcano 2008

  5. Imshennik, Nadiozhin, Chechetkin, Ivanova, Domogatsky… • Formation of the neutrino-sphere. • Accretion of the envelope on the core. • Kelvin cooling of the new-born neutron star. Vulcano 2008

  6. Binding energy emitted as 99% Neutrinos of all flavors 1% Kinetic energy 0.01% Optical luminosity Astrofisica neutrinica

  7. Raffelt et al. Vulcano 2008

  8. Vulcano 2008

  9. Neutrino ’84, 11th Int. Conf.on Nutrino Physics and Astrophysics 562 563

  10. Main interactions in scintillator • Inverse β decay: • Neutrino-elettron scattering: • Neutral currents interactions: • Charged currents interactions: Vulcano 2008

  11. Arteomovsk BST Soudan Kamioka GranSasso Homestake Mt Blanc Sudbury KGF The muon depth-intensity curve (underground data): curves are calculated by Bugaev et al., 1998

  12. Fe (2 cm) Fe (10 cm) H=5200 m.w.e. 72 counters Liquid Scintillator Detector (LSD) 6 m 90 tons ofСnH2n (n~9), 200 tons of Fe 4.5 m 8m Vulcano 2008

  13. On line print of five pulses on 23 febbrury 1987 at 3 hr, 52 min, i.t., detected at Mt. Blanc LSD experiment Vulcano 2008

  14. Vulcano 2008

  15. +4 +6 +8 +10 +12 Jones Shelton mv McNaught 1987А Jones Discovery Mont Blanc Kamioka, IMB, Baksan Radio (21cм) Sk – 69o202 S W (У В) ? Shelton Feb24 Feb25 Vulcano 2008 UT 0h 2h52m 7h36m 9h22m 15h54m

  16. DETECTED NEUTRINO SIGNALS Mont Blanc 5 pulses E > 5 MeV UT 2:52:36.8 + 2 ms Kamioka 11 “ 8 7:35:35 + 1 min + (7 pulse at 7:54:22) ? IMB 8 “ 25 7:35:41 + 5 ms BST (2+5) “ 10 2:52:34 and 7:36:06 (+ 2s-54s) The main signal comes from electron antineutrinos: nep ne+ followed by e+e_ annihilation producing 2 g’s, detectable in scintillator but not in water. The Mont Blanc signal (5.8 < Evis< 7.8 MeV) corresponds to 4.6 < Evis< 6.6 MeV in water, at the limit to be detected in Kamioka. Vulcano 2008

  17. - 60 s - 60 s + 60 s + 60 s shift Kamioka-LSD correlations LSD Dt = 1.0 ms 0 Kamioka Dt= 60 sec

  18. T: from 1:45 to 3:45 LSD: 91 events, f=0.72/min Eth ≥ 5-7MeV K-II: 191 events, f=1.4/min Eth ≥ 7.5MeV (20 hits)

  19. C LSD-KAMIOKANDE Coincidences in 34 hours- 17-2 hrs intervals – 11.45-22 Feb. – 21.45 - 23 Feb 10 Dt = 0.5 s 8 Shift = 7.0 s 1462 events at LSD 2890 events at Kamioka Shift = 6.9 s 6 Expected: 2.03 4 2 11.45 17 .45 23.45 5.45 11.45 17.45 2-22 2-23 TIME U.T

  20. 91 Mt. Blanc events 240 Baksan events

  21. Annals New YORK Academy of Sciences, Vol. 571, pag. 577 New York 1989 Ed. by Ervin Fenyves

  22. Coincidences Mt.Blanc-Kamioka NC = 191•91•2•0.5/7200 = 2.4 NO = 9 Coincidence window Dt = + 0.5 s Bin width: 2 hours Coincidence time: 34 hours Kamioka time + 7 seconds Mt. Blanc event time 1:45 – 3.45 U.T. Vulcano 2008

  23. n, p Neutrino interactions in iron n, Fe ne+56Fe 56Co+e-

  24. e e e СnH2n СnH2n СnH2n Vulcano 2008

  25. A rotating collapsarImshennik Ryazhskaya Collapse Model View from aside 5 h later View from above Vulcano 2008

  26. The LVD detector in Gran Sasso 840 scintillator counters, 1.5 m3 each, are inserted in modules holding 8 counters each. The modules are grouped and stacked together to form three towers of 35 modules each. The scintillator of ach counter (1.2 tons) is watched from the top by 3 PMTs (15 cm diameter). Vulcano 2008

  27. INTERNAL Counters (M=570 tons) Topology EXTERNAL Counters (M=430 tons) TOP VIEW FRONT VIEW Vulcano 2008

  28. Neutrino Burst Detection in LVD ne tagging through detection of delayed g from n capture at low energy threshold, efficiency 60%. - NC and CC interactions on carbon nuclei useful for neutrino oscillation. Vulcano 2008

  29. LVD 10 years High duty cycle (>99.5% since 2002) Fiducial Active Mass (M~ 900 tons since Jun/2001) Vulcano 2008

  30. Active Mass and Duty Cycle

  31. stability survey • The scintillator stability has been monitored for about 2 years using a 252Cf n-source and periodically measuring: • n-capture efficiency • n mean capture time • Both do not show any hint of variation or degradation. • Other measurements are done on smaller samples by directly measuring transmittance and light yield. n-capture efficiency mean capture time Vulcano 2008

  32. Galaxy survey LVD  4919 days  rate of Galactic Gravitational Stellar Collapses [D≤20kpc] < 0.18 event/year 90% c.l. SUPER KAMIOKANDE  rate of Galactic Gravitational Stellar Collapses [D≤100kpc] < 0.32 event/year 90% c.l. Vulcano 2008

  33. The SNEWS Network Alarm to scientific community SuperNova Early Warning System LVD SK BNL server SNO Every experiment looks for SN burst and send alarms at fixed rate (1/week); the network must be as much as possible fault tolerant. • Give prompt information toastronomical community. • Doing online coincidence, reduce to zero fake alarm. • Triangulation possible Vulcano 2008

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